Brain mechanisms that change the priority of future
information based on their behavioral relevance

The ability of the human brain to change the priority of which
information is being processed is a key property that underlies
day-to-day functioning. We constantly shift our attention to those
stimuli or events that are behaviorally important. This thesis is
focused on understanding the biological neural mechanisms by which
the brain accomplishes this feat and what the long term
consequences are. In the studies described in this dissertation we
asked participants to do computer-run cognitive tasks during which
we recorded high-temporal resolution electroencephalography (EEG)
measures of their electrical brain activity. We used rewards to
change the behavioral relevance of certain events, and investigated
how the brain was able to facilitate the processing of those
events. Besides improved behavioral performance for rewarded
stimuli or events, as measured by fast and accurate responses, EEG
results indicated that the brain was able to boost the neural
activity in less than a second following a reward in those neural
populations involved in the processing of those potentially
rewarding stimuli or events. These mechanisms were very similar to
those involved in the control of attention, suggesting that
attention is guided by reward. Moreover, these prioritization
processes do not only work on a moment-to-moment basis but can also
occur on a much longer timescale, by changing the priority of
stimuli by integrating multiple encounters of rewards. Accordingly,
as a consequence, the evaluation and use of rewards enables the
brain to continually facilitate optimization of specialized neural
pathways in the processing and responses to incoming
information.